The present invention pertains to a compact, which is useful in a tool, that comprises a hard metal substrate that is bonded to a superhard member. The superhard member and the substrate are bonded together in such a fashion to from the compact so as to facilitate the attachment of the compact to the tool. Typical tools that utilize such hard compacts include earth boring (or engaging) bits (e.g., roof drill bits, conical style cutting bits (both underground mining and construction), and oil and natural gas drill bits (e.g., fixed cutter bits, roller cone bits and hammer bits).
The substrate of the hard compact typically comprises a cobalt cemented tungsten carbide wherein the cobalt content can range between about 3 weight percent and about 16 weight percent and wherein tungsten carbide (and recognized impurities) comprise the balance. The cobalt-tungsten carbide material may also include recognized additive such as titanium, tantalum, niobium and the like. Further, the substrate may comprise other metallic materials such as, for example and without limitation, steel, tool steel and refractory metals such as, for example and without limitation, titanium, niobium, molybdenum and their alloys.
The superhard member of the hard compact may comprise a thermally stable polycrystalline (TSP) diamond member wherein the cobalt has been either partially or fully (which is preferred) leached from the diamond structure. Although the basic method to make TSP is known to those skilled in the art, a brief description of the process for manufacturing TSP is set forth. A diamond table is a layer of randomly oriented individual diamond “crystals” that are bonded together at bonding lines known as diamond-diamond boundaries in the art. The bonding of individual diamond crystals in the diamond table forms a lattice structure. A metallic binder, typically cobalt, serves as a catalyst in the formation of bonds between individual diamond crystals, and is often found within the interstitial spaces in the diamond table's lattice structure. Cobalt has a significantly different coefficient of thermal expansion as compared to diamond, so upon heating of the diamond table, the cobalt will expand more rapidly than the diamond table, causing cracks to form in the lattice structure, and eventually resulting in deterioration of the diamond table.
In order to impede crack initiation and propagation in the diamond table resulting from differential thermal expansion, strong acids are used to “leach” the cobalt from the diamond lattice structure. The removal of cobalt from the diamond table results in thermal stability of the diamond table at higher temperatures but also increases its brittleness. Accordingly, in certain cases, only a select portion (measured in any dimension) of a diamond table is leached, in order to gain thermal stability without losing impact resistance. As used herein, the term TSP diamond member includes both of the above (i.e., partially and completely leached) materials.
The cobalt-leached TSP diamond member may be coated with nickel or tungsten metal or one or more of titanium metal and titanium carbide applied via physical vapor deposition (PVD) techniques. Representative patent documents that disclose this kind of coated TSP diamond include United States Application Publication No. US 2006/0254830 to Radtke for a THERMALLY STABLE DIAMOND BRAZING and U.S. Pat. No. 6,575,350 B2 to Evans et al.
The superhard member may also comprise a silicon carbide-bonded TSP diamond member or a silicon compound-bonded TSP diamond member. U.S. Patent Application Publication No. US2005/0230156 A1 to Belnap et al. discloses a method for the formation of a TSP diamond member using silicon or silicon carbide as a “getter” material in conjunction with cobalt-coated diamond particles. Representative patent documents that disclose a TSP diamond member that uses silicon include U.S. Pat. No. 4,151,686 to Lee et al. for a SILICON CARBIDE AND SILICON BONDED POLYCRYSTALLINE DIAMOND BODY AND METHOD OF MAKING IT, and U.S. Pat. No. 4,664,705 to Horton et al. for a THERMALLY STABLE POLYCRSYTALLINE DIAMOND, which mentions silicon infiltration of a diamond skeleton.
In addition, the superhard member may comprise any one of cubic boron nitride or silicon carbide or silicon nitride or alumina or SiAlON ceramics or conventional polycrystalline diamond.
In rotary well drilling operations, oil and natural gas bits are used to drill a bore hole in geological formations. These earth boring or engaging bits can include rotary cone bits, fixed cutter bits and hammer bits. In either type of earth boring bit, a steel body (or matrix) typically contains apertures that receive the hard compacts. These hard compacts (or inserts) are used as shearing, rock cutting, crushing, chipping or abrading elements. U.S. Pat. No. 5,159,857 to Jurewicz for a FIXED CUTTER BIT WITH IMPROVED DIAMOND FILLED COMPACTS, U.S. Pat. No. 5,662,183 to Fang for a HIGH STRENGTH MATRIX MATERIAL FOR PCD DRAG BITS, and United States Patent Application Publication US2005/0247491 A1 to Mirchandani et al. for EARTH-BORING BITS illustrate typical earth boring (or engaging) bits that use hard compacts. Each one of the above patent documents is hereby incorporated by reference herein.
U.S. Pat. No. 6,607,249 to Taitt for CONICAL BIT PENETRATOR POCKET PROTECTOR FOR EARTH DISPLACEMENT EQUIPMENT describes a typical conical style of cutting bit. Such a conical style of cutting bit has a hard member, which could be a hard compact, contained in a socket at the axial forward end thereof. U.S. Pat. No. 5,429,199 to Shierer et al. for CUTTING BIT AND CUTTING INSERT describes a typical roof drill bit. Such a roof drill bit has a hard member, which could be a hard compact, affixed to the axial forward end of the bit body. International Patent Application Publication No. WO 95/16530 to Kennametal Inc. for POLYCRYSTALLINE DIAMOND COMPOSITE CUTTING INSERT FOR ATTACHMENT TO A TOOL discloses a conical bit, as well as a roof drill bit, that includes a diamond composite hard member at the axial forward end thereof. Each one of the above patent documents is hereby incorporated by reference herein.
Hard compacts useful in the above-mentioned earth engaging bits have been made from cemented tungsten carbide. Cemented tungsten carbide typically comprises a metal binder (e.g., cobalt, nickel or iron) with the balance tungsten carbide particles. The most common binder metal is cobalt wherein the cobalt content ranges between about 3 weight percent and about 16 weight percent. Cemented tungsten carbide may also include other additives. The exact composition of the cemented tungsten carbide compact depends upon the desired properties for the specific drilling application. Exemplary compositions of cemented tungsten carbide suitable for use in earth engaging bits are set forth in the following patent documents: U.S. Pat. No. 5,219,209 to Prizzi et al. for a ROTATABLE CUTTING BIT INSERT (discloses cobalt cemented tungsten carbide inserts that comprise between about 5 to about 13 weight percent cobalt with the balance tungsten carbide, and wherein a specific composition comprised 5.4-6.0 weight percent cobalt with the balance tungsten carbide), and U.S. Pat. No. 6,945,340 to Bise et al. for a ROOF BIT AND INSERT ASSEMBLY (discloses tungsten carbide-cobalt alloys that comprise 5.4 weight percent cobalt with the balance tungsten carbide, 6.3 weight percent cobalt with the balance tungsten carbide, and 6.0 weight percent cobalt with the balance tungsten carbide).
In addition to cemented tungsten carbide compacts, it is typical that hard compacts have comprised sintered diamond on top of a cemented (cobalt) tungsten carbide substrate. In this regard, U.S. Pat. No. 1,939,991 to Krusell for a DIAMOND CUTTING TOOL OR THE LIKE AND METHOD OF MAKING THE SAME discloses a diamond cutting tool that has diamond inserts held in a cemented tungsten carbide matrix. As briefly described below, additional patent documents describe other hard compacts that comprise diamond and tungsten carbide.
In some prior art cutting tools, the diamond component of the tool was formed by the conversion of graphite to diamond. U.S. Pat. No. 3,850,053 to Bovenkerk for a CUTTING TOOL AND METHOD OF MAKING SAME describes a technique for making cutting tool blanks by placing a graphite disk in contact with a cemented tungsten carbide cylinder and exposing both simultaneously to diamond forming temperatures and pressures. U.S. Pat. No. 4,259,090 to Bovenkerk for a METHOD OF MAKING DIAMOND COMPACTS FOR ROCK DRILLING describes a technique for making a cylindrical mass of polycrystalline diamond by loading a mass of graphite into a cup-shaped container made from tungsten carbide and diamond catalyst material. The loaded assembly is then placed in a high temperature and pressure apparatus where the graphite is converted to diamond. U.S. Pat. No. 4,525,178 to Hall for a COMPOSITE POLYCRYSTALLINE DIAMOND shows a composite material which includes a mixture of individual diamond crystals and pieces of pre-cemented carbide. U.S. Pat. No. 4,148,368 to Evans for ROCK BIT WITH WEAR RESISTANT INSERTS shows a tungsten carbide insert for mounting in a rolling cone cutter which includes a diamond insert embedded in a portion of the work surface of the tungsten carbide cutting insert in order to improve the wear resistance thereof.
U.S. Pat. No. 5,159,857 describes a hard compact that has a hard metal substrate and a member of polycrystalline diamonds. To make the compact, diamond powder is placed in the inner volume of the metal substrate. This composite is subjected to a treatment under heat and pressure that sinters the diamond into a raw blank. The raw blank comprises a member of integrally formed polycrystalline diamond surrounded by the hard metal substrate. U.S. Patent Application Publication No. us2005/0230150 to Oldham et al. shows the use of coated diamond members in drill bit for an earth boring application. Other patent documents show the use of cutting inserts that employ diamonds wherein these patent documents include U.S. Pat. No. 6,234,261 B1 to Evans et al, U.S. Pat. No. 6,575,350 B2 to Evans et al. and PCT Patent Publication No. WO 99/28589 to Radtke.
Still other patent documents pertain to hard compacts for use in drill bits or components of hard compacts that use TSP diamond. In this regard, these patent documents include the following: U.S. Patent Application Publication No. US2006/0060391 to Eyre et al. for a THERMALLY STABLE DIAMOND POLYCRYSTALLINE DIAMOND CONSTRUCTION, U.S. Patent Application Publication No. US 2005/0263328 to Middlemiss for a THERMALLY STABLE DIAMOND BONDED MATERIALS AND COMPACTS, U.S. Patent Application Publication No. US 2006/0254830 to Radtke for THERMALLY STABLE DIAMOND BRAZING, U.S. Patent Application Publication No. US 2006/0191723 to Keshavan for THERMALLY STABLE POLYCRYSTALLINE DIAMOND MATERIALS, CUTTING ELEMENTS INCORPORATING THE SAME AND BITS INCORPORATING SUCH CUTTING ELEMENTS, and U.S. Patent Application Publication No. US 2006/0060390 to Eyre for THERMALLY STABLE DIAMOND POLYCRYSTALLINE DIAMOND CONSTRUCTIONS.
While the hard compacts that comprise a hard metal substrate bonded to a superhard (e.g., polycrystalline diamond) member have been used in tools such as earth boring or engaging bits, there remains a need to provide an improved hard compact that can be used in such tools. There also remains a need to provide such a compact that is of such a nature to facilitate the attachment of the hard compact to the tool.
Further, even though techniques used to braze TSP diamond to tungsten carbide exist (see Suryanarayana et al., “Novel Methods of Brazing Dissimilar Materials”, Advanced Materials & Processes (March 2001) and U.S. Pat. No. 5,523,158 to Kapoor et al. for BRAZING OF DIAMOND FILM TO TUNGSTEN CARBIDE and PCT Patent Publication WO 00/34001 to Radtke for Microwave Brazing Process and Brazing Composition for TSP Diamond), there remains a need to be able to bond together a superhard member and a substrate that have heretofore been difficult to satisfactorily bond together to form a hard compact. There also remains a need to be able to bond together a superhard member and a substrate that have heretofore been difficult to satisfactorily bond together to form a hard compact that is of such a nature to facilitate the attachment of the hard compact to the tool.